| 摘要 |
<p>A navigation apparatus includes: an acquisition unit for receiving a satellite signal from satellites and demodulates the satellite signal to acquire ephemeris data; a storing unit for storing the ephemeris data; a time measuring unit for measuring a valid time of the ephemeris data from timing of acquisition of the ephemeris data; and a control unit for making the acquisition unit reacquire new ephemeris data before the valid time of the ephemeris data elapses in the time measuring unit.
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